[12] What remains of the moated castle are the form of the central church courtyard and the outer walls of the manor house.

When the last count von Katzenelnbogen died in 1479, Darmstadt fell to Henry III, Landgrave of Upper Hesse.

[7] When Philip I took over the government offices in 1518, the castle was destroyed for the first time in an attack by Franz von Sickingen.

[7] Landgrave George I considerably extended the castle from 1567 to a Renaissance complex and secured it with moats and bastions.

Christoph Müller and Jakob Wustmann[14] developed the old moated castle into a residential palace.

[11] In 1842, the university and state library and the grand ducal collection with natural history cabinet moved in.

[11] Since the 18th century the castle has been less and less inhabited by the grand dukes and other members of the ruling family who settled in more comfortable premises, most of which were destroyed in World War II.

Meanwhile, more and more institutions were admitted in the vacant old residential palace and some of the rooms were reserved for state guests.

[23] As of 2023[update], the castle is the seat of the Technische Universität Darmstadt and the German-Polish Institute [de].

[29][17][30] The Baroque part of the castle (De-la-Fosse-Bau or Neuschloss) consists of a three-storey[10] southern and west wing on an angular floor plan.

[26] From the town, a fortified gate leads directly through the baroque castle into the southern courtyard.

[44] The palace museum shows objects belonging to the former landgraves and Grand Dukes of Hesse-Darmstadt.

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